>>17901557
It was not so easy, yeah, there were internal passports, and depending on time you would need permission to just move away from village to city, because kolkhoz premier might want to keep you there, working. But that was it first, later, especially due to industrialization, there was a moment into cities.
On the other hand, you might be assigned to move, get an education, there is some vacancy somewhere - bam, you are moved there.
>>17901567
Call it ethnostate if you want, but it was not the one that was really protective of ethnicity, or if it was then there were other factors - like people not wanting to move there. Look at Estonia, Latvia, northern Kazakhstan, for example, with large Russian minorities. They also had their own soviet republics, or ethnostates as you call them.